Many of the harmful effects of alcohol are the result of abuse on specific occasions by social drinkers. Such abuse is especially likely to occur as a result of sharing a few drinks with other members of a small, informal group in the context of a commercial drinking establishment such as a bar or tavern. This research has three goals: 1) to further document the extent to which alcohol abuse is anchored in the context of in-bar, small groups; 2) to describe the organization and dynamics of such small groups, including validating a typology of such groups which employees of commercial establishments could use to predict and prevent abuse; and 3) to develop strategies of intervention to be used by commercial establishment employees to prevent abuse, and thereby the harmful outcomes likely to result from it. During phase one a random sample of commercial drinking establishments in a large metropolitan area will be intensively observed. Average consumption for the establishment will be estimated to discover whether taverns in fact do substantially differ in drinking norms. Small groups of patrons from 2-9 in number will be observed to calculate consumption and abuse, including strength of drinks, speed of drinking and duration of drinking session. Variance within the group will also be measured and groups will be classified into one of four regulatory types. During the second phase a range of groups classified by regulatory type will be videotaped and their members interviewed. The organization and dynamics of the four types of groups will be studied to discover ways in intervene in groups which are not sufficiently self-regulating to prevent abuse. During the third phase experimental techniques of intervention by tavern employees will be tried. The success of these interventions will be evaluated. Those which promise success will be incorporated into training materials to be provided tavern employees.